When you've got a threesome going with two girls, one is laying on top of the other, and you alternately penetrate each one, i.e. insert penis into the top girl, then withdraw and insert it into the bottom girl, then the top one again, then the bottom, ad infinitum until orgasm. This is flying the cock. Originally coined by Jeffy of RSD.
I flew the cock with Sydney and her mom last night dude, it was awesome--Jeffy would be proud!
While in the doggy-style postion on a trampoline one must seamlessly transition to a full nelson and begin to bounce. At this time an accomplice is needed to initiate a double bounce which provides the air time. When in the air the bitch begins to flail strikingly similar to a cockroach in mid flight.
When people say 'I don't give two cents', or 'I dont give a ___', instead, say 'I don't give a flying cockroach!' or 'I don't give a flying TWO cockroaches!', to make it even moredramatical.